Field of Invention
The present invention relates to a semiconductor device, in particular, to such a semiconductor device having subword drivers for driving subword lines.
Description of the Related Art
In a memory-type semiconductor device such as a DRAM (Dynamic Random Access Memory), memory cells are disposed on intersections between the subword lines and bit lines. The driving process of the subword lines is carried out by subword drivers, and when the subword line is driven to an active potential, the memory cell is connected to the corresponding bit line. On the other hand, during a period in which the subword line is driven to a non-active potential, the memory cell and the bit line are kept in a cut-off state.
The non-active potential of the subword line in the DRAM is normally set to a negative potential lower than the ground potential (see JP-A No. 2013-157044). This is because by setting the subword line to the negative potential, the off-leak current of cell transistors included in the memory cell is reduced, thereby making it to possible to prevent an information retaining characteristic from being deteriorated due to a disturbance phenomenon. The disturbance phenomenon refers to a phenomenon in which, when a certain subword line is repeatedly accessed, the information retaining characteristic of a memory cell connected to another subword line adjacent thereto is lowered.
In this case, however, when the negative potential to be given to the subword line is too low, a GIDL (Gate-Introduced Drain Leakage) current increases due to a voltage between the gate and drain.